6-substituted-unsaturated aldehydes by decomposition of 3-hydroperoxy-1, 5-cyclooctadiene with ferrous ions and a cupric salt



United States Patent 3 401,193 G-SUBSTITUTED-UNSA TURATED ALDEHYDES BY DECOMPOSITION 0F 3-HYDROPEROXY-1,5-CY- CLOOCTADIENE WITH FERROUS IONS AND A CUPRIC SALT William J. Farrissey, Jr., Northford, Conn., assignor, by mesne assignments, to Esso Research and Engineering Company, Elizabeth, N.J., a corporation of Delaware No Drawing. Filed Mar. 18, 1964, Ser. No. 352,933 6 Claims. (Cl. 260-488) The present invention is directed to acyclic a,;8-unsaturated aldehydes produced from 1,5-cycloo-ctadiene. More particularly, the invention is concerned with the decomposition of the a,fl-hydroperoxide formed in the autoxidation of 1,5-cyclooctadiene; In its more specific aspects, the invention is directed to the decomposition of 3-hydroperoxy- 1,5-cyclooctadiene in the presence of a ferrous metal ion and a cupric salt.

The present invention may be briefly described as a method for producing acyclic o e-unsaturated aldehydes by the decomposition of the t p-unsaturated hydroperoxides, 3-hydroperoxy-1,5-cyclooctadiene, formed in the autoxidation of 1,5-cyclooctadiene, by reacting the hydroperoxide with a ferrous metal ion, preferably in the presence of a cupric salt.

The hydroperoxide starting material of the present invention is obtained in the oxidation of 1,5-cyclooctadiene. The oxidation is preferably carried out by bubbling oxygen through the 1,5-cyclooctadiene in a solution of benzene or decane and in the presence of azoisobutyronitrile at a temperature within the range of about 50 to about 75 C., preferably about 60 C.'The use of an initiator which produces free radicals at the operating temperatures, such as azoisobutyronitrile, hastens the uptake of oxygen and reduces or eliminates an induction period. Other initiators may be used, such as benzoylperoxide and t-butyl peracetate; however, the initiator selected should be such that undesirable metals are not introduced into the system. It is preferred that the oxidation of 1,5-cyclooctadiene be carried out as a separate step so as to recover the hydroperoxides in relatively pure-form.

In the oxidation of 1,5-cyclooctadiene, two hydroperoxides are formed, namely 3-hydroperoxy-l,S-cyclooctadiene and fi-hydroperoxy-1,4-cyclooctadiene, and a peroxidic oil. The two hydroperoxides are recovered from the peroxidic oil by a mixed solvent technique wherein the hydroperoxides are selectively dissolved into the solvent, whereas the peroxidic oil is insoluble. Although other mixtures may be used, a mixture of an excess of petroleum ether and benzene has been found to be effective to selectively dissolve the two hydroperoxides. The hydroperoxides are recovered in pure form by removing the solvent by evaporation or some equivalent manner.

The hydroperoxide mixture obtained from the autoxidation of.1,S-cyclooctadiene is decomposed, according to the present invention, with a ferrous metal ion. The afiunsaturated hydroperoxide, 3-hydroperoxy-1,5-cyclooctadiene, unexpectedly reacts to form a considerable quantity of a ti-unsaturated aldehydes. The treatment of the hydroperoxide mixture may be carried out in a variety of reaction media. If the treatment is carried out with only the ferrous metal ion, C a,[3-unsaturated dialdehydes are produced. The production of the aldehydes is thought to be the result of the cleavage reaction as follows:

3,401,193 Patented Sept. 10, 1968 It is thus observed thatthe a,/3-unsaturation of the alkoxy radical appears to be of such an unusual substitution that the ring is opened to form the aldehyde rather than producing only the more expected ketone. When only the ferrous metal ion is used, however, a mixture of the C dialdehydes is produced from which the identification of specific compounds is difficult.

In accordance with the present invention, the decomposition of the hydroperoxide mixture is accomplished in the further presence of cupric salts whereby specific unsaturated C aldehydes are produced. When the hydroperoxide mixture consisting of 3-hydroperoxy-l,5-cyclooctadiene and 6-hydroperoxy-1,4-cyclooctadiene is treated with a ferrous metal ion at room temperatures in the presence of a cupric salt, besides the formation of some cyclooctadienone, two C o fiunsaturated aldehydes are formed which differ only in cis,trans-isomerism about the u,;3-double bond. The two aldehydes have the following formulae:

trans where X is the anion of the cupric salt or the solvent.

A further aldehyde formed is the Q y-unsaturated aid hyde having the formula:

where X is the anion of the cupric salt or of the solvent.

The decomposition of the hydroperoxide mixture, according to the present invention, is therefore carried out in the presence of both a ferrous metal ion and a cupric salt to produce useful C unsaturated aldehydes. Suitable ferrous salts which may be employed in the decomposition of the hydroperoxides are ferrous sulfate, ferrous chloride, or other ferrous salts of strong and weak acids. It is preferred to use cupric acetate as the cupric salt. However, cupric salts having the formula, Cu++(X) where X is selected from the group consisting of a halogen, azide, OR or where R is a lower alkyl, may also be employed. The decomposition of the hydroperoxides is preferably carried out at room temperatures (25 -30 C.) but may be can ried out at temperatures from about 0 to about C. The decomposition of the hydroperoxides is usually carried out in the solution of the ferrous and cupric salts. However, the decomposition may take place in an inert solvent which is inert both to the hydroperoxides and the aldehydes formed, such as acetonitrile, acetic acid or the like.

The present invention is further illustrated by the following examples which are set forth to merely illustrate and not to limit'the persent invention.

Example 1 In a one-liter flask equipped with condenser, highspeed stirrer, oxygen-inlet tube and thermowell was placed 200 cc. (176.6 g., 1.63 mols) of cis,cis-l,S-cyclooctadiene and 0.4 g. of azoisobutyronitrile. The solution was heated to 60 C. and pure oxygen gas admitted. Oxidation was continued until 4.23 liters (0.19 mol. 11.7%) of oxygen had been absorbed. Unreacted olefin was removed by vacuum evaporation at 40 C. after which there remained 25.52 g. of a thick viscous oil. The oil was separated into hydroperoxide and peroxidic oil components by treatment with a petroleum ether-benzene mixture. On addition of 204 cc. of petroleum ether and 41 cc. of benzene and cooling to C., two layers were formed. The upper layer was decanted and solvent evaporated from it to yield 12.37 g. (0.088 mol, 46%) of hydroperoxide material. The insoluble peroxidic oil material weighed 12.42 g. (0.089 mol, 47%). Upon analysis of the hydroperoxide material, 3-hydroperoxy-1,5-cyclooctadiene and 6-v hydroperoxy-1,4-cyclooctadiene were found.

Example 2 One hundred grams of cyclooctadiene were Placed in a reaction vessel. Oxygen was introduced at a temperature of 76 C. for about 90 mintues and at 60 C. for about 64 minutes wherein 5.04 liters of oxygen were absorbed. The crude product obtained Was treated with 250 cc. of petroleum ether and 50 cc. of methanol. This mixture was cooled in an ice bath, and the solvents were decanted leaving peroxides. The hydroperoxides, 3-hydroperoxy-1,5-cyclooctadiene and 6-hydroperoxy-l,4-cyclooctadiene, were recovered by vacuum distillation.

The foregoing examples illustrate the methods for preparing the desired hydroperoxide which is decomposed according to the present invention.

Example 3 To an aqueous solution of 1.4 g. of ferrous sulfate heptahydrate was added slowly over a period of 30 minutes a solution of 1.52 g. of cyclooctadienyl hydroperoxide (a mixture as formed in Example 1) in 50% aqueous isopropanol. After two hours at room temperature, the reaction mixture was concentrated under vacuum, diluted with a saturated solution of sodium chloride and extracted with ether. Evaporation of the ether gave 1.14 g. of product which is about 30% dimeric dialdehyde. The dimeric dialdehyde remained undistillable at 90 C. and 0.3 mm. The NMR spectrum of the dimeric dialdehyde indicates that the material is predominantly a,,B-unsaturated.

Example 4 The reactor consisted of a four-neck, 1000 ml. roundbottom flask containing a thermometer, dropping funnel, a mechanical stirrer and 50 ml. syringe. In the flask was placed 25 g. of cupric acetate in 475 ml. of acetonitrile. From the dropping funnel was added 20 g. of ferrous sulfate heptahydrate in 100 ml. of water. From the syringe was added simultaneously with the ferrous sulfate g. of cyclooctadienyl hydroperoxide (a mixture as formed in Example 1) in 35 ml. of acetonitrile. Throughout the addition, the flask was immersed in a water bath maintained at zero degrees. Addition of the hydroperoxide took 1.5 hours while the addition of the ferrous sulfate solution took twice as long. The reaction mixture was stirred an additional one hour at room temperature after which it was filtered into a one-liter flask and most of the solvent evaporated. The remaining solution was poured into 500 ml. of water and extracted with three 100 ml. portions of ether. The ether extracts were washed, dried and the ether evaporated to give 9.11 g. of product. From the product was distilled a material boiling at 70 C. at 0.2 mm. which was identified as 6-acetoxyocta-2,7- dienal. Examination of the aldehyde by NMR showed that the aldehyde was predominantly cis. Upon further 4 a distillation of the product at C. and 0.005 mm., about one-third of the product remained undistillable. The undistillable material consisted of C dialdehyde.

Example 5 In the flask of a reactor as described in Example 4 was placed 30 g. of cupric acetate monohydrate in ml. of acetic acid. The syringe contained 12.00 g. of cyclooctadienyl hydroperoxide (a mixture as formed in Example 1) in 30 ml. of acetic acid. The addition funnel contained 27.80 g. ferrous sulfate heptahydrate in 100 ml. distilled water and one drop of 6 N sulfuric acid. Both hydroperoxide and ferrous sulfate solutions were added slowly to the rapidly stirred solution of copper salt. The addition of the hydroperoxide took approximately one hour, whereas, addition of the ferrous sulfate required twice as long. After all the reagents had been added, the mixture was stirred at room temperature for an additional three hours. The reaction mixture was filtered into a one-liter flask and concentrated on a Rinco evaporator. The remaining product was dissolved in chloroform and extracted repeatedly with distilled water to remove acetic acid. Drying and evaporation of the chloroform solution gave 10.49 g. of crude product. The crude product was distilled in a small spinning band column to give four fractions; fraction one consisting of a mixture of u,B-unsaturated ketones and alcohols, B.P. 3l-50 C. at 0.3 mm.; an intermediate fraction; fraction three consisting of a mixture of calf-unsaturated aldehyde acetates, B.P. 63.5 80 C. at 0.3 mm.; and a residue fraction. The O o-unsaturated aldehyde acetates were predominantly trans-aldehyde.

' Example 6 The procedure of Example 4 was duplicated except cupric chloride was used instead of cupric acetate. The aldehyde formed was 6-chloroocta-2,7-dienal.

As illustrated in the example above, it was found that in solvents, such as acetic acid or non-acidic solvents, with a drop or so of sulfuric acid added, the transaldehyde is formed; whereas, in isopropanol or acetonitrile the sis-aldehyde is predominant. Further, it was found that the cis-aldehyde may be changed to the trans form by merely mixing in the presence of iodine.

The unsaturated aldehydes formed according to the present invention are useful as chemical intermediates. Further, the v c-unsaturated aldehydes may be further reacted to form a-amino acids. Likewise, the n p-unsaturated aldehydes are useful as monomers in polymerizations, especially as modifiers due to their functional substitutions which may be used as cross-linking agents or as dye acceptors.

The unsaturated aldehydes may be hydrogenated, for example, in an ethyl alcohol solution with palladium-oncharcoal catalyst to form the saturated aldehyde. The saturated aldehydes are known useful products.

Further, the cap-unsaturated aldehydes of the present invention may be reacted with ozone in the presence of a solvent such as methanol, acetic acid, etc., and the resulting ozonolysis product oxidized with oxygen to form the substituted dicarboxylic acid. For example, the ozonolysis and oxidation of the products of both Examples 4 and 5 yield This substituted dicarboxylic acid is the precursor for the a-amino acid, glutamic acid, which is one of the 0 H OH=CH-OH2CHz(iJH-CH=CH2 where X is selected from the group consisting of a halogen, azide, -OR and it 0 CR and R is a lower alkyl.

2. A composition of matter having the following formula:

6 3. A composition of matter having the following formula:

4. A method for decomposing 3-hydroperoxy-1,5-cyclooctadiene to form acyclic a,,B-unsaturated aldehydes which comprises reacting said hydroperoxide with a ferrous metal ion in the presence of a cupric salt wherein the anion of said salt is selected from the group consisting of halogen, azide, --OR and 0 ll OCR where R is lower alkyl at a temperature about 0 to about 50 C. in an inert solvent.

5. A method according to claim 4 wherein the solvent is acetic acid and a small amount of sulfuric acid and the trans-aldehyde is formed.

6. A method according to claim 4 wherein the solvent is selected from the group consisting of isopropanol and acetonitrile and the cis-aldehyde is formed.

References Cited Chemical Abstracts, 54: 217%; 54: 10826i.

LORRAINE A. WEINBERGER, Primary Examiner. V. GARNER, Assistant Examiner.

U.S. DEPARTMENT OF COMMERCE PATENT OFFICE Washington, D.C. 20231 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,401,193 September 10, 1968 William J. Farrissey, Jr.

It is certified that error appears in the above identified patent and that said Letters Patent are hereby corrected as shown below:

Column 6, lines 3 to 6, the formula should appear as shown below:

Signed and sealed this 10th day of March 1970.

(SEAL) Attest:

Edward M. Fletcher, Jr.

Attesting Officer Commissioner of Patents WILLIAM E. SCHUYLER, JR. 

1. A COMPOSITION OF MATTER HAVING THE FOLLOWING FORMULA: 